Process for preparing metal soap mixtures



Unlted States Patent Int. Cl. B01j 1/16 U.S. Cl. 252-400 Claims ABSTRACTOF THE DISCLOSURE Mixtures of a metal soap (I) melting below 40 C. andof a metal soap (II) not melting below 140 C. are formed by reacting asaturated, straight chain C -C fatty acid with a suitable metal compoundof metal (II) at a temperature above 100 C., in a melt of metal soap(I), or in an excess of the fatty acid. Organic additives melting below140 C. may be present.

This invention relates to a process for preparing a mixture of metalsoaps.

Metal salts of long-chain fatty acids, also known as metal soaps, may beprepared either by a precipitation method carried out in an aqueousmedium or by a fusion process in anhydrous media. Whereas almost allmetal soaps can be prepared by the precipitation method, only a limitednumber of them can be produced by the fusion process.

In the fusion process, metal oxides, hydroxides and metal salts ofvolatile acids, such as formates, acetates or carbonates, are reacted inthe melt with the corresponding fatty acids. The required temperaturesare normally in the range of from 120 C. to 140 C., by reason of therelatively low reactivity of some of the reactants and of thedisplacement of reaction equilibrium towards formation of a metal soapby elimination of the water of reaction or of the volatile acid whichacted as metal carrier. The applicability of the fusion process isdetermined by two conditions, namely:

(1) Both the fatty acid employed and the metal soap formed must bestable at the reaction temperature, and the metal soap in particularmust not undergo discolouration or tend to resinify.

(2) At the reaction temperature, the melt must be of such thinly-flowingconsistency as to render a correct mixing of the reactants possible.

Although the condition of thermal stability at 120 C. to 140 C. issatisfied by most of the fatty acids and metal soaps, many of the latterdo not melt in this temperature range or, if they do, cannot form athinly-flowing melt. For example, among the metal soaps of stearic acid,only lead, zinc, magnesium and cadmium stearates display a sharplydefined melting point and yield thinly-flowing melts; others, likedibasic lead stearate and lithium stearate, do not melt at all, or donot have a sharply-defined melting point but transform into a plasticstate with several transition temperatures, as in the case of calcium,barium, strontium and aluminium stearates.

The first-mentioned, low-melting group of metal soaps are referred tohereinafter as Type I soaps, while the soaps having high meltingtemperatures are designated as Type II soaps. The metal soaps belongingto the highmelting or plastifying group II could be prepared hithertoonly by the precipitation method which, while yielding purer and morevoluminous products than the fusion method, is substantially morecomplicated and expensive, the production costs being further increasedby the more complicated equipment and the additional drying processinvolved. In addition, there are a number of applications which do notrequire small particle sizes, for example the stabilization ofpolyvinylchloride.

Metal soaps prepared by the fusion method, e.g. lead stearate, havealready been used for stabilizing polyvinylchloride. In order to achievea synergistic stabilizing effect, combinations of metal soaps ofdifferent metals, e.g. the known systems made up of barium-cadmiumlaurate, leadcalcium stearate and zinc-barium laurate, are employed.

A method of preparing metal soap combinations has now been found, makingpossible the preparation of metal soap combinations consisting of ametal soap of Type I yielding a thinly-flowing and thermally stablemelt, and of a plastic or non-melting metal soap of Type II by a verysimple fusion process.

According to the present invention, there is provided a process forpreparing a mixture of metal soaps comprising from 10 to 40% by weightof at least one metal soap melting below 140' C. and yielding athinly-flowing melt (Type I), and 60 to 70% by weight of at least onemetal soap which does not melt or melts only above 140 C. (Type II). Inthis process, a :metal soap of Type II is prepared by reacting asaturated, straight-chain fatty acid having 8 to 24 C-atoms with a metaloxide, hydroxide or metal salt of a volatile acid at a temperature aboveabout C. in a melt of a Type I metal soap, or in an excess of the fattyacid the excess of which is then converted into the Type I metal soap.

Optionally, one or more organic components which have a melting pointbelow C., which are compatible with the soaps and which do not reactwith the reactants, can be present in the mixture.

The Type II metal soap is thus prepared in a liquid medium, which neednot be eliminated after the reaction, because it is a component of thedesired metal soap mixture, and which may contain up to about 20% byweight of one or more organic compounds melting below 140 C.

This molten medium comprises either the melt of the first-obtained metalsoap of Type I or of a molten fatty acid, which is employed in such aquantity that its excess after preparation of the Type II metal soapwill suflice for conversion to Type I metal soap. In the final phasethere are obtained either dispersions of Type II metal soaps in the meltof Type I metal soaps or eutectic melts of the two metal soap types, ora solution of the Type II metal soap in the melt of the Type I metalsoap with a viscosity sufiiciently low to allow intimate mixing.

The metal soap mixtures prepared by the present process contains as itsType I metal soap preferably one or more of the soaps of astraight-chain fatty acid having from about 8 to about 24 C-atoms and ofzinc, cadmium or magnesium, and the normal lead soap of these fattyacids. The preferred Type II metal soaps are those formed by the metalslithium, potassium, sodium, barium, calcium, strontium and aluminiumwith straight-chain fatty acids having from about 8 to about 24 C-atoms,as well as basic lead salts, such as monoand di-basic lead soaps ofthese fatty acids.

In order to facilitate the reaction or to lower the viscosity, it isadvisable in some cases to employ organic additives melting at about 25C., which do not hinder the intended application of the metal soaps andwhich are not incompatible therewith. Where the metal soap mixtures areintended for use as stabilizers for polyvinylchloride, the organiccomponents used may be lubricants or plasticizers of the most diversechemical composition. The conditions determining their applicability arethat they must be capable of forming melts in the temperature range offrom about 25 C. to about 140 C., and, Where the metal component isconstituted by a metal oxide or hydroxide should not react with themetal component. The organic component melting in the range of fromabout 250 C.

component melting in the range of from about 25 C. to about 140 C. is inmost cases employed in an amount varying between and about 20% by weightof the total mixture. However, in certain cases it may be advantageousto employ larger amounts of one or more organic additives, for example,where the metal soap is to be used as a stabilizer for polyvinylchlorideand the organic component is a compound which is to be incorporated asplasticizer into the plastic in large amounts.

The organic component can be a phthalic acid ester, such as diphenylphthalate, dibenzyl-phthalate or dicyclohexyl-phthalate; a hydrocarbon,such as a natural paraffin, a synthetic parafiin or a polyethylene-wax;a fatty alcohol, such as palmityl alcohol, stearyl alcohol; a wax ester,such as cetyl palmitate, myristyl palmitate or stearyl stearate; anatural Wax such as carnauba wax; a triglyceride, such as glyceroltri-12-oxy-stearate, glycerol tripalmitate, glycerol tristearate; or afatty acid amide such as stearic amide and ethylenediamine distearate.

The lowermost limit of the quantity of organic component is determinedby the viscosity of the mixture of Type I and Type II metal soapsobtained. The quantity of organic component must be such, that thereaction mixture is sufficiently viscous to ensure a thorough mixmg.

The ratio of Type I and Type II metal soaps will be selected inaccordance with the intended application and the viscosity of the meltat the relevant preparation temperature. The viscosity of the meltincreases proportionally to the content of Type II metal soaps, so thatthe limit of sufficient miscibility is soon reached. The composition ofthe mixed products varies within the following limits:

Percent Type I metal soap 40-10 Type II metal soap 60-70 Organiccompounds melting below 140 C 0-20 The metal components which can beemployed in the present process in forming soaps I and II include theoxides, hydroxides, formates, or acetates of mono-, diand tri-valentmetals; for example, lead, zinc, magnesium, cadmium, calcium, barium,strontium, aluminium, lithium, potassium, sodium, cerium, bismuth,manganese, tin, nickel and beryllium. The fatty acids which can be usedare saturated, straight-chain fatty acids with from about -8 to about 24carbon atoms. Instead of pure fatty acids, there can also be employedfatty acid mixtures as obtained by industrial processes. The lattercontain varying amounts of unsaturated fatty acids like oleic acid,linoleic acid, linolenic acid or ricinoleic acid. As a rule, the amountof unsaturated fatty acids should not exceed to of the total amount offatty acids. The unsaturated fatty acids normally form plastic soaps andtherefore do not hinder the process. Larger quantities of unsaturatedacids would only alfect the milling properties of the final products,and are therefore undesirable.

The process of the invention is illustrated by the following examples.

EXAMPLE 1 Lead stearate, calcium stearate, 1:1

8285 grams (g.) of stearic acid are heated to about 120 C. and areadmixed with 4.815 g. of calcium oxide, the latter being introduced insmall portions. When the reaction is ended, 14.95 g. of litharge areadded to the resulting mixture, again in small portions. In order toaccelerate the reaction, a few drops of water are sprayed into the melt.The reaction temperature can then be increased up to 150 C.

EXAMPLE 2 Barium-cadmium laurate: 37.5% barium laurate, 62.5% cadmiumlaurate 81.7 g. of lauric acid are heated to 130 C. to 140 C.

4 hydroxide. The latter is added in small portions. When the reaction iscompleted, 14.55 g. of barium hydroxide monohydrate are strewn into theresulting reaction mixture. The product is then poured into a pan forcooling and can be ground thereafter without diificulty.

EXAMPLE 3 Barium-cadmium laurate: 30% barium laurate, 50% cadmiumlaurate, 20% lubricant 65.4 g. of lauric acid are heated together with10 g. of a O -C fatty alcohol and 10 g. of spermaceti to C. to C. Theresulting mass is admixed while stirring with 14.92 g. of cadmiumhydroxide. After completion of the reaction, 11.63 g. of bariumhydroxide monohydrate are strewn in. If the melt becomes too viscous,the temperature can be increased to about C. to C.

EXAMPLE 4 Barium-cadmium soap from hydrolysed coconut fatty acid: 51.6%barium soap, 28.4% cadmium soap, 20% lubricant 62.1 g. of hydrolysedcoconut fatty acid are heated together with 20 g. of a C C fatty alcoholto about 120 C. to 130 C., and 7.36 g. of cadmium hydroxide are strewninto the resulting mixture while stirring. After completion of thereaction, 16.55 g. of barium hydroxide are introduced. The reactiontemperature can be raised to 140 C. to 150 C.

What we claim is:

1. A process for preparing a mixture of metal soaps consistingessentially of (a) from about 10 to about 40 percent by weight of atleast one metal soap melting below about 140 C. of a saturated,straight-chain fatty acid having from about 8 to about 24 carbon atomsper molecule and a metal selected from the group consisting of zinc,cadmium and magnesium, or a normal lead soap of said acid, and (b) fromabout 60 to about 70 percent by weight of at least one metal soap notmelting below about 140 C. of said acid and of a metal selected from thegroup consisting of lithium, potassium, sodium, barium, calcium,strontium, aluminum, cerium, bismuth, manganese, tin, nickel andberyllium, or a basic lead salt of said acid, which comprises reactingsaid acid with a metal compound selected from the group consisting of anoxide, a hydroxide and an acetate or formate, wherein the metal thereofis identified in (b) above, at a temperature above about 100 C. in amelt of soap (a).

2. The process of claim 1, wherein reaction is effected at a temperaturefrom about 100 C. to about 150 C.

3. The process of claim 1, wherein reaction is effected in the presenceof up to about 20 percent by weight of an organic additive selected fromthe group consisting of a wax, a long chain alcohol, a paraffin, a fattyacid ester, a fatty acid amide, a triglyceride and a phthalic acid estermelting between about 25 C. and about 140 C.

4. A process for preparing a mixture of metal soaps consistingessentially of (a) from about 10 to about 40 percent by weight of atleast one metal soap melting below about 140 C. of a saturated,straight-chain fatty acid having from about 8 to about 24 carbon atomsper molecule and a metal selected from the group consisting of zinc,cadmium and magnesium, or a normal lead soap of said acid, and (b) fromabout 60 to about 70 percent by weight of at least one metal soap notmelting below about 140 C. of said acid and of a metal selected from thegroup consisting of lithium, potassium, sodium, barium, calcium,strontium, aluminum, cerium, bismuth, manganese, tin, nickel andberyllium, or a basic lead salt of said acid, which comprises reactingan excess of the molten fatty acid with a metal compound selected fromthe group consisting of an oxide, hydroxide and an acetate or formate,at least one metal thereof being identified in (b) above and then aftercompletion of the reaction convert the surplus of fatty acid with ametal compound selected from the group consisting of an oxide, hydroxideand an acetate or formate, at least one metal thereof being identifiedin (a) above.

5. The process of claim 1, wherein the mixture comprises approximatelyequal parts by weight of lead stearate and calcium stearate, formed byreacting about 3 molar proportions of stearic acid with 1 molarproportion of calcium oxide and then with about 0.6 molar proportion oflitharge at a temperature from about 120 C. to about 150 C.

6. The process of claim 1, wherein the mixture comprises about 37.5percent by weight of barium laurate and about 62.5 percent by weight ofcadmium laurate, formed by reacting about 1.6 molar proportions oflauric acid with 1 molar proportion of cadmium hydroxide and then withabout 03 molar proportion of barium hydroxide monohydrate at atemperature of about 140 C.

7. The process of claim 3, wherein the mixture comprises about percentby weight of barium laurate, about percent by weight of cadmium laurateand about 20 percent by weight of equal parts by weight of a C -C fattyalcohol mixture and of spermaceti, formed by reacting about 3 molarproportions of lauric acid with one molar proportion of cadmiumhydroxide in the presence of said alcohol mixture and said spermacetiand then with about 0.6 molar proportion of barium hydroxide monohydrateat a temperature from about C. to about C.

8. The process of claim 3, wherein the mixture comprises about 52percent by weight of barium soaps of coconut fatty acids, about 28percent by weight of cadmium soaps of coconut fatty acids and about 20percent by weight of a G -C fatty alcohol mixture, formed by reactingabout 5.5 molar proportions of coconut fatty acids with one molarproportion of cadmium hydroxide in the presence of said alcohol mixtureand then with about 1.7 molar proportions of barium hydroxide at atemperature from about 120 C. to about 150 C.

9. A mixture of metal soaps formed by the process of claim 1.

10. A mixture of metal soaps formed by the process of claim 5.

References Cited UNITED STATES PATENTS 2,417,429 3/1947 McLennan 252362,695,910 11/1954 Asself et al. 25236 3,194,823 7/1965 LeSuer et al.260-414 MAYER WEINBLATT, Primary Examiner I. GLUCK, Assistant ExaminerUS. Cl. X.R.

UNITED STATES PATENTOFFICE CERTIFICATE OF CORRECTION Alfred Szczepaneket a1.

ears in the above identified It is certified that error app ebycorrected as patent and that said Letters Patent are her shown below:

Column 1, line 14, "40 C." should read 140 C.

t melting in the range of from Column 2, line 72, cancel "componen about250 C."

Signed and sealed this 2nd day of March 1971.

(SEAL) Attest:

Edward M. Fletcher, 1:. WILLIAM E. SCHUYLER, IR.

Commissioner of Patents Attesting Officer

